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=Introduction= Renin (pronounced /ˈriːnɨn/ REE-nin) is also known as angiotensinogenase, a monospecific enzyme that participates in the body's renin-angiotensin system (RAS). Renin is responsible for catalyzing the rate-limiting step in the synthesis of angiotensin II. Once renin and pro-renin bind to the pro-renin receptor, there is an increased enzymatic activity and additional physiological effects.

Structure
Renin belongs in a family called aspartic proteases which use an aspartate residue for the catalysis of their peptide substrate. X-ray diffraction experiments has shown there is a striking similarity among the structures of aspartyl proteases. Renin consists of two homologous lobes each containing an aspartic acid. Between the lobes is the active site, which is catalyzed by the aspartic acid residues, a characteristic trait of all aspartate proteases. Renin in its full mature form has a mass of 37 kDa and contains 340 amino acids. Uniquely from other proteases, Renin has two β-carboxyl groups of Asp32 and Asp215 which protrude from each of the two lobes into the active site and has a large flap covering the Active site.



Function


Renin plays a key role in the Renin-Angiotension sysmtem (RAS). It is essential in facilitating the conversion of angiotension to angiotension II, which is the active component of the RAS system. This system is responsible for the regulation of blood pressure, stimulation of the secretion of aldosterone which effects the salt and water balance.
 * Angiotensinogen is released into the bloodstream by the liver.
 * Likewise, Renin is secreted by the kidneys into the bloodstream where is meets with angiotensinogen.
 * Once united, angiotensinogen form the decapeptide angiotensin (ANG) I.
 * ANG I is then activated by Angiotensin converting enzyme (ACE) to form the octapeptide ANG II.
 * ANG II then acts on specific receptors such as ones responsible for vasoconstriction or the release of aldosterone from the adrenal cortex.



=References=